In south orange county really the only legal place worth pursuing is Laguna Niguel Lake, I've caught a lot of bass out of that lake from shore. You can catch them a heck of a lot of ways there too. Outside of LNL there's some city park lakes around the county Laguna Lake(fullterton), Tri City, Craig, Ralph B clark, Huntington has central park and mile square, and Santa ana has a few ponds as well.
If you want to get on a bigger body of water I'd recommend the smaller SD lakes like Dixon, Wohlford, Murray, or Miramar. They're easier to fish than the bigger lakes from the rental boats and Wohlford is the only one with a bow mount trolling motor.